1. Field of the Invention
The present invention relates generally to a seal structure used in various electronic apparatuses, such as a portable device, for water stopping, dustproofing, etc., and more particularly, to a seal structure, an electronic apparatus, and a sealing method that enable the passage of a signal line, such as a flexible cable.
2. Description of the Related Art
An electronic apparatus, such as a portable device, requires a waterproofing function corresponding to the use and function of the electronic apparatus, and is conventionally provided with a sealing structure that prevents the ingress of water, etc.
An electronic apparatus related to such a seal structure that maintains a waterproofing function even when a substrate is held between packings is disclosed in Japanese Patent Application Laid-Open Publication No. 2002-198664. According to this apparatus, a packing in contact with a flexible substrate has a rib-like projection having a uniform height and width, and the projection is fitted in a slot formed on the trunk and back lid of the apparatus. When the apparatus's housing is closed, the projection elastically deforms in a direction in which the projection sticks closely to the side face of the substrate to fill a gap, which suppresses the ingress of water (see ABSTRACT, FIG. 1, etc.).
A waterproof structure built in a portable terminal device having an upper unit and a lower unit that can be folded via a hinge is disclosed in Japanese Patent Application Laid-Open Publication No. 2004-47968. According to the waterproof structure, a space between an FPC and a connection cable, and a case that is outside the FPC and connection cable is filled with a seal packing at the boundary between the hinge and the upper unit and between the hinge and the lower unit (see ABSTRACT, FIG. 1, etc.).
Conventionally, a seal structure in an electronic apparatus, such as a portable device, is provided by such methods as injecting a sealant in a spot to be waterproofed or dustproofed, integrally molding or gluing together a signal line, such as a flexible cable, and a rubber, press fitting a signal line into a case hole, and inserting a packing. The methods of injecting a sealant and of gluing together a flexible substrate and a rubber accompany a demerit that the solidification of the sealant or adhesive takes some time to allow dust to stick to the sealant or adhesive before their solidification, thus requiring a process for controlling the solidification of the sealant or adhesive and preventing dust sticking. This is disadvantageous in terms of a manufacturing process. The method of integrally molding a flexible cable and a rubber accompanies limitations on the type of the rubber to use and the condition of the flexible cable, which leads to a disadvantage of higher manufacturing costs.
The seal structure may be provided as a structure such that a sponge gasket or rubber gasket is simply held between housings. This structure, however, may be incapable of sealing up a gap formed between a flexible cable and the gasket depending on the thickness of the flexible cable and the hardness of the gasket, bringing a concern of incapability in preventing soaking, dust intrusion, etc.
In a structure that a cable is held between a housing and a sealing material, a gap is formed between the cable and the housing when the housing is hard and the cable is thick. If this gap cannot be filled, the structure cannot offer sufficient water stopping and dustproofing functions.
In a structure including two packings that are disposed to sandwich a flexible cable therebetween, a housing incorporating the packings therein is required to have high assembling precision, and a gap may be formed between the cable and the packings when the cable is thicker and the packings are harder. This gap prevents the structure from offering sufficient water stopping and dustproofing functions.
Japanese Patent Application Laid-Open Publication Nos. 2002-198664 and 2004-47968 provide no disclosure and suggestion concerning the above requests and problems, and do not disclose or suggest a configuration, etc., that is solution to the requests and problems.